Tuesday, February 12, 2008

Will the Uranium ever run out?

Imagine a business, that is quite literally running out the ear with raw materials. So much so, that no one has bothered to sit down and count them all. Then along comes someone who says, you are running out of raw materials, so you are going to shut your business down soon. He shows you a report that only counts a small fraction of the raw materials avaliable. "You see that," he says. "You are runinng out of raw materials.

Such is the case with Uranium. No one knows how much Uranium there is, because no one has produced a truely systamatic account. There is however a whole lot.

The “proven reserve” estimates are flawed for two primary reasons. First of all they do not consider the fact that very little effort, or money, has been put towards uranium exploration thus far. Second, they do not adequately account for the tiny effect that uranium ore price has on final nuclear power price, and the maximum allowable prices that they use to determine “economically recoverable” reserves are far too low.

The effort made thus far in uranium exploration is absolutely negligible compared to the many hundreds of billions (trillions?) of dollars that has been invested in oil and gas exploration, technology development, and extraction, etc… As the history of oil and gas shows, as these investments are made, more and more reserves are found. As discussed earlier, we stopped exploring for new uranium deposits relatively soon after we started looking, since we rapidly found “all we need”, due to sluggish nuclear expansion and the glut of uranium from decommissioned weapons. Now, even the majority of known sites and mines lay idle due to the low ore price (although this is starting to change).

As the price of uranium ore goes up, significant resources will go into uranium exploration, and many new deposits will be found, including many high-grade ore deposits that were simply never discovered. It is likely that the amount of uranium in yet-to-be-discovered high-grade (low cost) ore deposits greatly exceeds that which exists in currently-known high-grade deposits. In addition to these high-grade deposits, a large number of lower-grade deposits, both currently known and yet to be discovered, will become economical and will be developed. This is what happened with oil and gas, and it is even more clear that this is what will happen with uranium. Given that uranium produces about a million times as much energy as an equivalent mass of oil, gas, or coal, the amount of energy locked up in uranium (in the earth’s crust) exceeds that locked up in fossil fuels by several orders of magnitude. This bodes well concerning the amount of uranium that will/can be eventually discovered and developed.

One of the primary reasons why there is no market for breeder reactors, is that the uranium supply is so plentiful that many easily accessed potential uranium sources are ignored, simply because it would cost a few dollars more to extract uranium than current market pays for uranium. Some of these sources include:

In addition, there is a world wide stock of one million tons of depleted uranium, all of which can fuel into breeder reactors. This does not count the hundreds of thousands of tons of supposibly spent reactor fuel, mostly sitting idle at nuclear plants, where it is called unfortunately, nuclear waste.

And of course there has been no prospecting for uranium in over 30 years.

Deffeyes & MacGregor estimate that there are 40 trillian tons of Uranium in the earth's crust. Even with avaliable mining technology deposits with uranium concentrations as low as 10 - 20 ppm can be mined with an energy output gain of 16 - 32 times energy input. According to Deffeyes & MacGregor data, that would be over 80 billion tons of uranium.

Breeders reactors produces 100 times as much energy from each pound of natural uranium than old fassion Light Water Reacors do. Thus a 50 year uranium supply for light water reactors would last 5000 years, with breeder reactors. In addition to uranium, the world is well supplied with thorium. Thorium can be breed into fissionable U233. Thorium is 4 times as plantiful in the earth's crust as uranium.

Easily and inexpensively extractable uranium and thorium can sustain a high energy, world wide economy for tens of thousands of years.

The most significant issue then is the efficient use of uranium and thorium as reactor fuels. Right now, uranium is not used to anything like its greatest possible efficiency. Current reactor technology, is based primarily on the use of U235 to create chain reactions. U235 constitutes 0.7% of natural uranium. During the reactor fuel cycle, perhaps 0.3% of the original U238 is transformed by nuclear alchemistry into reactor grade plutonium and burned.

That means that the energy of 99% of all U238 is not tapped by current nuclear technology. How much of it can be tapped? The answer is all of it. Given technology we already posses, we have the potential to tap 100% of the energy in natural uranium. The reason why we don't do it, is that reactor manufactuers and power companies think it is cheaper to run new uranium through a reactor, than to extract the total energy from the uranium they have partially used.

Although the technology already exist to use abundant thorium as a reactor fuel, reactor manufacturers and public funding agencies have directed little effort to achieve its potential.

All this does not stop people from claiming we are running out of Uranium.

Update 2/13/08 (From a comment I made in Peak Oil today:

Uranium is 99.3% U238, and 0.7% U235. About 0.3% of the U238 gets transmutated into plutonium in LWRs and gets burned. The 0ther 99% of the U238 can be transmutated into PU239 in breeder reactors. That makes the energy efficiency of breeders 100x of that of LWRs. The price of heavy water in not nearly as expensive as you have indicate. The current cost of heavy water @ $300 per kilogram is far cheaper than Uranium enrichment. Thus heavy water use is cost effective in reactorsa, because it produces far superior burn rates for reactor fuel. In fact so called spent nuclear fuel, can be very inespensively burned in heavy water reactors.

The heavy water in a CANDU requires a capital investment equal to approximately 20 percent of the cost of the plant. Overall, the initial capital cost of a CANDU is ten to twenty percent higher than a comparable light water reactor depending on local labor costs.

On a lifecycle basis, however, lower fuel costs tend to make the two systems roughly comparable on price, so decisions between the two are often made on the desire for independence, the availability of local labor, the availability of capital investment, the existing infrastructure of the customer, and the availability of vendor incentives.

However your account of breeder technology made serious omissions. Argonne National lab successfully operated the Experimental Breeder Reactor II (EBR-II) for 30 years. The primary reason why breeding technology is not in vogue is that Uranium is still so plentiful, and manufacturers and utilities still think it is cheaper to stick ever more new uranium and plutonium into reactors, rather than breed more. Civilian power reactors are currently burning up cold war era nuclear bombs and warheads. Getting rid of the nuks keeps fuel costs low. There are other breeder technologies which you failed to mention including the molten salt reactor, which breeds thorium. Thorium is 4 times as common as uranium in the earths crust.
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You scoff at the notion of extracting Uranium for sea water, yet the Japanese have already developed the technology to do it.
http://nextbigfuture.com/2007/11/two-proposals-for-mining-ocean-for-720....

I stated in my previous post I noted that with energy input to recovery ratios possible with existing extraction technology, more that 80 Billion tons of uranium are recoverable. We can expect on this basis to obtain another 320 billion tons of thorium, enough to last the human race for a very long time.

11 comments:

I know it's kind of premature, but is there any reason we can't get uranium and thorium from space? We are, after all, talking about a timeframe tens of thousands of years in the future, and it seems like the energy density could conceivably make it worthwhile. It's not something to be pursued right now, but it does shine a new light on the supply of these "non-renewable" resources- once extraterrestrial sources are taken into account, these fuels are just as "renewable" as the hydrogen being fused in the sun.

That's the point, but I would kind of like to have a talking point to respond to "sustainable=forever" types of arguments. Being able to argue that "there's five billion years' worth of thorium in the asteroid belt" is a possible response. Never mind that we won't need to in any conceivable amount of time.

The consistent 3.3 ppb U in seawater is in chemical equilibrium. If it were being depleted, we would expect that additional U would be leached and put in solution from ocean bottoms, hydrothermal vents and cold seeps, and terrestrial sources (primarily through tidal pumping on the continental shelves, with some from rivers and other discharges). If we extracted a billion tons over hundreds of years, it is more likely that the oceans will contain nearly 4.5 billion tons than be reduced to 3.5+ billion tons.

Is this a "renewable" energy source?

The 0.7% of natural U U-235 is our only natural nuclear fuel source. Using it generates a small amount of Pu-239 from U-238 in U fuel.

Disposing of "spent fuel" is throwing away the remaining U-235 (roughly 20%?) and the small amount of Pu-239. Except for the question of whether U being replenished from the oceans is a "renewable" source, this is NOT renewable.

However, recycling used fuel enables using our only natural fissile isotope source to generate (breed) Pu-239, and U-233 from Th-232.

In this case we can produce more nuclear fuel than we use every year for millions of years. Nuclear fuel is, at least, a "renewable energy source."

Charles,I have book-marked your site and intend using it to refer people to who question nuclear power, as it is tedious to answer the same questions over and over.I argue here that a lot of the questions are in fact disingenuous, as they have already made up their minds on nuclear power, that they don't like it, and there is no answer, say to waste disposal, which will satisfy them:http://anz.theoildrum.com/node/3600#comment-303958

Charles, I am using your blog to answer those who critique nuclear power - it gets really tedious to answer the same questions over and over, and you rebut far more ably than I.I recently argued that many of the questions, say about waste, were disingenuous anyway, as they had already made up their minds that no possible answer would satisfy them:http://anz.theoildrum.com/node/3600#comment-303958

Your site is a valuable resource for those who wish to argue the case for nuclear, together with Bill'sMany thanks.

Why are we still calling these things "breeders?" It makes people think they produce weapons grade stuff, when gen-IV fast reactors don't. This even lead the Clinton administration to shut down our integral fast reactor program in 1994 because they thought it was a proliferation risk, like the purex process for MOX. An extremely unwise decision.

The 4.5 tons of uranium in sea water figure ignores the fact that rivers flush about 32,000 tones per year of uranium into the ocean. This has led nuclear physicist Bernard Cohen to argue that the energy source could outlast the sun.